I was thinking hot glue the rope to itself. Or looping the rope like I tie my boot laces... hummm can I explain this to make sense... place a loop along the back of the horn before wrapping. Then wrap with the loop inside the coil. When finished wrapping there should be a small part of the loop still sticking out that you can thread the end through. It kind of becomes a self-containing knot because you then pull the starting end of the rope and it tightens and secures everything. I'm pretty sure I got it from girl scouts but I don't remember the name of the knot.